Soon after having worked on the Operon you very quickly elaborate the replicon model with Sydney Brenner.
With Sydney, yes. Because we- it happened on a beach- I had already been thinking about it for a while. Because I had noticed that during the recombination systems, whether it be by conjugation or by phage transfer, when a piece of DNA was transferred, a piece of DNA- let's say a piece of DNA was transferred by which ever one of these mechanisms into a receiving cell, that piece of DNA would not replicate. It only replicated in certain conditions and when there was, for example, a certain segment of the phage's chromosome or of whichever- so, the conclusion is that there needed to be a site which allowed or didn't allow replication and in comparison, with the operator system, I constructed this thing with the replicator, with the difference that it needed to be positive. There were arguments to say- there needs to be a gene which makes protein, a product which acts on an area which allows replication, for example opens the DNA or whatever. That's it.
Which means that, basically, positive regulation didn't represent a problem for you. The idea that there could be a positive regulation next to a negative regulation.
None.
Which Monod found much more troubling.
Yes, but Monod believed that nature needed to be rational and have the same rationale as him. Which really isn't easy. And that's why he wanted all regulations to be negative. Since we had found successively three systems, phage, lactose, tryptophan, which were all negative regulations, hence nature was regulatero-negative.
Which was never confirmed.
In principle, it isn't necessarily obvious. That's it.
You believe a lot more in the diversity and resourcefulness of nature.
Yes, I always believed in bricolage. Bricolage, meaning using things as they are, and taking something old and making it into something new.
In fact, it's an idea that you are going to develop afterwards in the seventies.
Later yes. Yes, because evolution is a little like that. Evolution takes a structure and uses it, but not solely in the way in which it was used at the beginning, but to do other things at the same time. And so it resembles bricolage.
And it was a very successful concept. Everyone talks about bricolage nowadays.
Yes, but I think that it was a very reasonable idea. It annoyed quite a few people, because they didn't really like the idea that we were the product of bricolage. But in fact, it's still a very useful notion because that's how it works.

François Jacob (1920-2013) was a French biochemist whose work has led to advances in the understanding of the ways in which genes are controlled. In 1965 he was awarded the Nobel Prize in Physiology or Medicine, together with Jacque Monod and André Lwoff, for his contribution to the field of biochemistry. His later work included studies on gene control and on embryogenesis. Besides the Nobel Prize, he also received the Lewis Thomas Prize for Writing about Science for 1996 and was elected a member of the French Academy in 1996.

Michel Morange is a professor of Biology and Director of the Centre Cavaillès of History and Philosophy of Science at the Ecole Normale Supérieure. After having obtained a Bachelor in biochemistry and two PhDs, one in Biochemistry, the other in History and Philosophy of Science, he went on to join the research unit of Molecular Genetics headed by François Jacob, in the Department of Molecular Biology at the Pasteur Institute, Paris. Together with Olivier Bensaude, he discovered that Heat Shock Proteins are specifically expressed on the onset of the mouse zygotic genome activation. Since then he has been working on the properties of Heat Shock Proteins, their role in aggregation and on the regulation of expression of these proteins during mouse embryogenesis. He is the author of 'A History of Molecular Biology' and 'The Misunderstood Gene'.